<insert id="insert" parameterType="Mail" useGeneratedKeys="true" keyProperty="id_note">

insert into note(sender, from_address, subject, content, send_time)

values(#{sender}, #{fromAddress}, #{subject}, #{content}, #{sendTime})

<selectKey keyProperty="id_mail" resultType="int">

select LAST_INSERT_ID()

</selectKey>

</insert>

<!--这里可以获得刚插入表格的id，为后面attachment的插入提供了mailId字段-->

<select id="selectLastId" resultType="int">

select LAST_INSERT_ID()

</select>